Sugar-sweetened beverage consumption has increased greatly among children since the 1960s, i parallel with the pediatric obesity epidemic, and now accounts for >10%of energy intake amon adolescents. Several lines of evidence suggest that sugar-sweetened beverage consumption has remarkably strong effect on body weight in overweight children: 1) mechanistic studies indicate that human do not compensate fully for the energy in sugar-containing liquids;2) cross-sectional studies find consisten associations betweeen consumption of sugar-sweetened beverages and total energy intake or body weight 3) a longitudinal study found that risk of becoming obese in middle school students increased 60% for ever additional serving per day of sugar-sweetened beverage;4) short-term interventional studies found tha adults who substitute non-caloric for sugar-sweetened beverages loss weight;5) a school-based stud reported lower incidence of obesity among children counseled to reduce all soft drinks;6) our pilot dat indicate that the effect of decreasing sugar-sweetened beverage consumption on body weight in schoo children is highly correlated with baseline body weight, revealing a unique sensitivity among children abov the 85th percentile for BMI For this long-term, large-scale multi-site study, we have partnered with 5 high schools in the greate Boston area and a major regional supermarket. Participants will be 240 high school students who drink a least 1 serving of sugar-sweetened beverage per day and who have a BMI >85th percentile. Participant will be randomly assigned to intervention or control groups. The intervention, of 1-year duration, will b performed on the home environment (including delivery of non-caloric beverages as done in our pilot study and at the school (including education and behavioral modification aimed at reducing sugar-sweetene beverage consumption), focusing both on participants and the parents. Our primary endpoint will be chang in BMI z-score at 2 years (1 year after conclusion of the intervention). The study has been designed t demonstrate definitively whether or not an intervention focused exclusively on beverage consumption i efficacious in the prevention and treatment of obesity in children. These results should have immediat public health application, and aid in the design of future, comprehensive obesity prevention interventions.